This invention relates to a seat belt system for vehicles of the type having a selectively engageable belt latch on buckles, and an accident indication device for generating an electrical signal in the event of deceleration forces indicating an accident. A system of this type was described in German Publish Unexamined Application No. (DE--OS) 30 20 505 published Dec. 10, 1981 in West Germany.
After accidents, the question is often raised as to whether the occupants of the vehicle had put on the seat belt in a functionally correct way or whether they had not put it on or whether there has a manipulation or tampering. In the case of active systems (belt tighteners), it is also of interest whether this system was triggered or not. By means of the known system, it can be determined only whether the buckle latch was latched in the belt buckle. However, this may also be the case when the occupant is not wearing the seat belt in a functionally correct way and is sitting on the latched seat belt.
The response to these questions is very important in the case of a reconstruction of an accident, in the case of medical experts' reports and for the purpose of court proceedings.
It is therefore an objective of this invention to further develop a seat belt system of the known type so that information can be obtained as to whether an accident took place with corresponding severity, whether the belt had been worn functionally correctly, but also whether manipulations took place in order to misrepresent this condition.
According to the invention, this objective is achieved by providing lock closure indicating switch means movable between open and closed positions in dependance on whether said belt latch is locked; first electrical indicating means arranged in series with the lock closure indicating switch means and the accident indicating electrical signal generating means; belt tension indicating switch means movable between open and closed positions in dependence on belt tension forces exceeding a predetermined valve corresponding to forces experienced when a passenger is retained by the seat belt during a vehicle accident; and second electrical indicating means arranged in series with the belt tension indicating switch means and the accident indicating electrical signal generating means in parallel to the lock closure indicating switch means and first electrical indicating means. In certain preferred embodiments the indicating elements are melt through fuses. Other embodiments utilize Coulomb cells. Depending on which of the two indicating elements has responded, exact information can be obtained on the past history when, after an accident, the belt latch mechanisms are secured and examined.
Further developments of preferred embodiments of the invention provide further electrical indicating means in parallel to the respective first and second electrical indicating means, to thereby enhance the number of possible different safety belt usage situations that can be monitored in an after-accident inspection.
Further objects, features, and advantages of the present invention will become more apparent from the following description when taken with the accompanying drawings which show, for purposes of illustration only, several embodiments in accordance with the present invention.